camelidfandomcom-20200214-history
CHARACTERIZATION OF DROMEDARIES (Camelus dromedarius) POPULATION IN TUNISIA
By Mohamed OULD AHMED ouldahmedmohamed@yahoo.fr The eco-climatic conditions (irregularity of pluviometry, high temperatures, continual winds, etc.) limit naturally the development of breeding in the Tunisian Southern arid and semi-arid regions. Nevertheless, there are geomorphologic sites offering conditions more favourable for the existence of the characteristic spontaneous grazing (Dhahar, El-Ouara, Djeffara, etc.). In Tunisia, these collective grazing represent the mainly available feed resources for dromedaries. The objective of this thesis was to describe conditions of breeding of dromedaries, to analyze their genetic diversity and revealing the perspectives of exploitation and valorisation of their products in sustainable breeding systems. Knowing that, the dromedary occupies a major place in the socioeconomic development of the breeders because the multiple functions and the services which it gets. However, pressures of diverse origins among which the population growth, the repetitive drought, the secular practices, threats the development of the dromedary. In this context, the present study was begun to determine the practices governing the management of the dromedary and the organization of its genetic structure. The knowledge of this information has a major importance for the elaboration of any strategy of exploitation and sustainable conservation, profitable and well targeted. The analysis of certain breeding practices showing that the traditional aspect remains dominant. Besides, we observed a timid trend towards the improvement of management and production. The dromedary conceals important "deposits" of production underexploited at present. The implemented of the breeding techniques and the adequate economic mechanisms will allow the valorisation of camel products. For better valorisation, the levying of the major constraint identified can be made by acting either on the animal, or on its environment (grazing, market, etc.) or on both (the animal and the environment) what is the ideal. The study of the genetic diversity was based on 8 loci microsatellites. A total of 34 alleles were detected in the three populations. The average of number of alleles per locus is 4.25 alleles per locus, percentage of polymorphism (P) is 100% and the heterozygosity (Hnb) is 0.61. The mean estimates of F-statistics were FIT= 0.15, FIS = 0.071 and FST = 0.083. These values were significantly different from zero (p<0.05) and suggest a moderate differentiation. An inbreeding rate of 15% was found. Estimated genetic distances revealed by the loci varied from 0 to 0.9 between dromedary individuals. The estimated genetic distances pair-wise showed 0.104 among Medenine-Tataouine, 0.280 between Kebili- Medenine and 0.29 between Kebili-Tataouine. The distance matrix was able to distinguish between two separate genetic entities: Nefzawa (Kebili) including Merzougui, G’oudi and M’hari ecotypes and the Aaradh group (Medenine and Tataouine) which includes Maghrebi and Khaouar ecotypes. Results of this study did not confirm the present classification established by dromedary herders. Which divides the population into five different ecotypes, apparently based on the sociogeographical criteria. These preliminary results showed that microsatellites are promising tools for breed characterisation. They indicated that investigated populations have high genetic variability and would be suitable as genetic stocks for conservation and sustainable utilisation programmes. This level of diversity and this genetic structure could be essentially the fact of the evolutionary history of the dromedary and especially the consequences of the reproduction strategies adopted by the breeders so facilitating the inbreeding and the genes flow. For the conservation of camel resources, the results of this thesis offer new perspectives for the dromedary conservation. The results inform about the characteristics of the camel population primordial for the preservation and the capture of the maximum of genetic diversity of the dromedary. The conservation and the valorisation of dromedaries necessitate the collaboration between the various interveners (profession, development and scientific research). This vision should formulate in four axes: 1) Organization of the sector, 2) Protection of dromedary and that concerns essentially institutional measures (incitements, legislations, economic policies, etc.), 3) Valorisation by the use of products and 4) Scientific research to answer the composed questions. As a matter of fact, let us hope that these results will improve and will guide programs of conservation and development of the camel in Tunisia.